Azo pigments containing oxdiazole rings



United States Patent 2,838,486 AZO PIGMENTS CONTAINING OXDIAZOLE nmos N0Drawing. Application July 6, 1955 Serial No. 520,368

Claims priority, application Switzerland July 7, 195-1 7 Claims. (Cl.260--157) This invention provides new oxdiazoles which, like, forexample, the compound of the formula i it contain at least one oxdiazolering and bound directly to that ring at least one aromatic nucleus whichis bound to an azo linkage.

The invention also provides a process for making the aforesaid newoxdiazoles, wherein an N(1):N(2)-diacylhydrazine, in which both of theacyl groups bound to the hydrazine radical are derived from carboxylicacid groups and at least one of the CO- groups is bound to anaryl-carbon atom of a radical which contains an azo linkage, is. treatedwith an agent bringing about ring closure. I

. The N(1):N(2)-diacyl-hydrazinescan be made by acylating hydrazines,and, for example, hydrazine may be acylated at both nitrogen atomslwiththe same radical of the constitution given abovev or two different acylradicals may be introduced in stages at least one of which radicals isof the aforesaid constitution. As acylating agents there areadvantageously used functional derivatives, for example, methyl estersor halides, for example, bromides or especially chlorides .of thecarboxylic acids used. There may bementioned, for example, the followingpossibilities: I

(a) Hydrazine is acylated at both nitrogen atoms with the derivative ofa carboxylic acid containing an azo linkage, and of which the carboxylicacid group is bound to an aromatic nucleus.

(b) Hydrazine is acylated at both nitrogen atoms with a derivative of acarboxylic acid capable of coupling, and of which the carboxylic acidgroup is bound to an aromatic nucleus, and the resulting carboxylic acidhydrazide is coupled with a diazo compound.

(0) Hydrazine is acylated in either order of succession with twodifferent carboxylic acid derivatives of the kind mentioned under (a).

(d) Hydrazine is acylated in either order of succession with twodifferent carboxylic acid derivatives of the constitution mentionedunder (b) and the resulting carboxylic acid hydrazide is coupled with adiazo compound.

(e) Hydrazine is acylated in either order of succession with twodifferent acid derivatives, of which one. has the constitution mentionedunder (a). o'r (b) above and the other has neither the constitutionaccording to (a) nor that according to (b). "Qne 'of'thefacidlderivatives, for example, that which i" astirientione'd maybe aderivative of a dicarboxyli c acid for 'example,"" maleic"anhydride, sothat 'diacyl-hydrazineis obtained containing asssass Patented June 10,1958 ice a free carboxylic acid group. By using a suitable agent capableof bringing about ring closure, such, for example, as thionyl chloride,the carboxylic acid group is converted into a carboxylic acid halidegroup simultaneously with the ring closure. An oxdiazole so obtainedwhich contains a carboxylic acid halide group may then be condensed withan a'rylamine, a diamine or hydrazine or a hydrazide, whereby in thelatter cases further ring closure to form an oxdiazole ring can becarried out.

(f) Hydrazine is acylated in either order of succession on the one handwith an acid derivative of the kind mentioned under (a) and on the otherwith an acid derivative of the kind mentioned under (12). If desired,after acylation with the carboxylic acid derivative of the kindmentioned under (b) above, irrespective of whether this is the first orsecond acylation, the intermediate compound may be coupled with adiazo-compound and there can be obtained, depending on the choice of thestarting materials, a symmetrical diacyl-hydrazine such as is alsoobtainable under (a) above, or an asymmetrical diacyl-hydrazine such asis obtainable under (0) above.

(g) Hydrazine, one or two mono-carboxylic acid derivatives and adicarboxylic acid derivative are condensed together in a suitable orderof succession in the molecular ratio 2:2: 1, so that for two molecularproportions of hydrazine and one molecular proportion of a dicarboxylicacid derivative either two molecular proportions or" the samemonocarboxylic acidderivative or one molecular proportion of each of twodifferent monocarboxylic acid derivatives may be used and at least oneacid derivative must be of the constitution mentioned under (a) or (b)above, and if an acid derivative as mentioned under (b) isused couplingwith a diazocompound follows the condensation with that acid derivative.

Thus, for example, two molecular proportions of an 7 of carboxylic acidhydrazide containing azo linkages :are

condensed with one molecular proportion of a dihalide of any desireddica-rboxylic acid. The products so ,obtained, although they contain twohydrazine groups and four acyl groups are referred to'herein asdiacyl-hydrazines for the sake of'simplicity.

As carboxylic acid derivatives of the constitution mentioned under (.a.)there may-be used, for example, derivatives of carboxylic acids of whichthepcarboxylic acid group is bound to a carbon atom of an aromatic ringsystem, which contains an azo linkage bound directly or through a bridgemember. to a further ringsystern or contains a carbon atom capable ofcouplingQ As such carboxylic acid derivatives theremaybe; mentioned forexample, derivatives of monoazo-dye'stuff carboxylic acids which can beobtained by coupling a diazotizedarhinobenzene carboxylic acidwith acoupling component free from sulfonic acid. and carboxylic acidi'groups, such as acylacetic acid ester or.,amide, .especial ly anacetoacetyl aminobenzene, a pyrazolone; especially ;a .3 -methyl-5pyrazolone,-.aphenol,,dihydroxyquinoline, and: i or p-naphthol suchasZ-hydroxynaphthalene, or 5; 8-dichlorol-hydroxynaphthalene.Advantageousresults are 'alsoobtained with talc-dyestuffs'containing,carboxylic acid groups obtained from diazo aco'mpounds. and, carboxylicacids capable of "couplingpsuch as l-phenykB-methYlf-S- pyraz'olone-T-or =4'*-carboxylic acid, andvalso acylacetylamino-benzene carboxylicacids' and cresotinic acids 'Qf particularjin terest';however, are theazo dyestuiis obtained from diazocompou'nds, especially those suitable.chosen for working according to (g).

for the production of ice colors, and coupling compounds of the formulaCOOK in which R represents a cyclic radical fused on to the 6-memberedring I in the manner indicated. As examples of such compounds there maybe mentioned 2-hydroxy-diphenyleneoxide 3 carboxylic acid,Z-hydroxycarbazole-3-carboxylic acid, 2-hydroxyanthracene-3-carboxylicacid and especially 2-hydroxynaphthalene-3-carboxylic acid. In makingsuch azo-dyestuffs it is of advantage to choose diazocompounds, whichare suitable for the production of ice colors, for example those of thebenzene series, which may contain in addition to the diazotized aminogroup other customary substituents, for example, halogen atoms such aschlorine, alkyl or alkoxy groups of low molecular weight, nitro groupsor acylamino groups.

As different carboxylic acid derivatives of the constitution mentionedunder (a) and (b) to be used according to (2) there may be usedderivatives of any desired carboxylic acid. In general it is ofadvantage to use derivatives of carboxylic acids of not too lowmolecular weight, advantageously those which contain more than one ring.

Any desired dicarboxylic acid derivatives may be In some cases it is ofadvantage to use dichlorides of simple dicarboxylic acids, for example,those of oxalic acid, fumaric acid, isophthalic acid or terephthalicacid, particularly dicarboxylic acids of the formula HOOCR -COOH, inwhich R represents a hydrocarbon radical having at the most 6 carbonatoms.

The reaction of the hydrazine with the carboxylic acid derivativesmay becarried out by methods in themselves known, advantageously in an organicsolvent. Among the carboxylic acids free from azo linkages, for example,Z-hydroxynaphthalene-3-carboxylic acid, it is in general of advantage touse a methyl ester as the functional derivative, and in the case ofproducts containing azo linkages it is of advantage to use carboxylicacid halides. It is known how to prepare such carboxylic acid chlorides,see, for example British Patent No. 730,384 filed February 27, 1952, byMax Schmid et al.

It is generally of advantage so to select the starting material that thediacyl-hydrazines obtainable in the manner described above contain nogroups imparting solubility in water, especially no sulfonic acid orcarboxylic acid groups.

As agents capable of bringing about ring closure there come intoconsideration for the present process more especially non-sulfonatingagents. Especially good results are usually obtained with thionylchloride. The ring closure is generally brought about with advantage byheating the diacyl-hydrazine with the ring-closing agent in an inertorganic solvent such, for example, as chlorobenzene or nitrobenzene.

The new oxdiazoles of this invention are valuable dyestulfs. Especiallyvaluable are the azo-dyestuffs free from groups imparting solubility inwater. These valuable pigments are generally distinguished by their veryalso by their resistance to heat and fastness to solvents. The latter isespecially useful, for example, in so-called pigment printing, that isto say, the printing process in which a pigment is fixed by means of asuitable adhesive such as casein, a hardenable artificial plastic,especially a ureaor melamine-formaldehyde condensation product, asolution or emulsion of polyvinyl chloride or polyvinyl acetate or otheremulsion (for example, an oil-ingood fastness to light, good fastness tomigration and v water emulsion or water-in-oil emulsion) on asubstratum, especially on textile fibers, but also on other flatstructures, such as paper (for example, wallpaper) or a fabric of glassfibers. The new pigments can also be used for other purposes, forexample, in finely divided form for coloring spinning masses used in themanufacture of artificial silk of viscose or cellulose ethers or estersor superpolyamides or superpolyurethanes, and also for producing coloredlacquers or lacquer formers, solutions and products of acetyl-cellulose,nitrocellulose, natural resins or artificial resins such aspolymerization or condensation resins, for example, aminoplasts,phenoplasts, polyvinyl chloride, polystyrene, polyethylene, polyacryl,rubber, casein, silicone and silicone resins. Furthermore, they can beused with advantage in the manufacture of coloring matters, cosmeticpreparations or laminated plates.

The new dyestuffs can easily be dispersed in the normal manner in massesor preparations of the aforesaid kind, and this can be carried out withadvantage at a stage in which such masses or preparations have notreached their final form. The operations necessary for forming theproducts, such as spinning, pressing, hardening, casting, sticking andthe like, can then be carried out in thepresence of the pigment withoutinterfering with any chemical reaction to which the substratum is to besubjected such as further polymerization, condensation or the like.

The following examples illustrate the invention, the parts andpercentages being by weight unless otherwise stated and the relationshipof parts by weight to parts by volume being the same as that of thekilogram to the liter:

Example 1 34.0 parts of the azo-dyestuff from diazotized 1-amin0-2-methyl-4-chlorobenzene and Z-hydroxynaphthalenc-B- carboxylic acid aresuspended in 300 parts of chlorobenzene, and the whole isheated at theboil accompanied by the distillation of any water present. As soon asthe distillate is clear, the whole is cooled to 70 C., 15 parts ofthionyl chloride are added, and the mixture is heated at the boilunderrefiux until appreciable quantities of hydrogen chloride are nolonger evolved. This is the case after 4-5 hours. The mixture is thenfiltered hot to remove small amounts of impurities and allowed to cool.The dyestutf acid chloride of the formula CH: DE

COCl

crystallizes on cooling in the form of dark crystals having a bronzelustre. The crystals are filtered off with suction and washed with coldchlorobenzene or benzene and dried in vacuo at 5060 C. i i i 35.9 partsof the acid chloride so obtained are stirred in 400 parts by volume ofanhydrous, chlorobenzenc with 3.5 parts of hydrazine hydrochloride, andthe whole is boiled for 8 hours under reflux. From the initiallydark-blue-red solution the hydrazine condensation product separates inthe form of an insoluble pale red substance accompanied by the evolutionof hydrogen chloride. After 6-8 hours the evolution of hydrogen chloridepractically ceases. The mixture is then allowed to cool to 70C. and 15parts of thionyl chloride are added. The whole is' then boiled .for afurther 10l2 hours under reflux, during which further large amounts ofhydrogen chloride and sulfur dioxide are evolved. When the condensationis finished, the mixture is filtered hot and the filter residue iswashed with boiling chlorobenzene until efs'segt'ss on; on O on horn isa pale red powder, which dissolves in Concentrated sulfuric acid with ablue-red coloration. It produces in artificial plastics, especially inpolyvinyl chloride, powerful through-dyed pure red colorations of goodfastness to migration and very good fastness to light.

Example 2 3529 parts of the-dyestuif acid chl'oridewof the'formulaobtainable from the dyestuif carboxylic acid in the manner described inthe first paragraph of Example 1 are boiled under reflux for hours in400 parts by volume "of chlorobenzene with 6.1 partstof hydrazinesulfate and 20 parts of pyridine. The whole-is cooled to 70 Ca and partsof thionyl chloride are added to the suspension of the hydrazinecondensation product. The mixture is then heated for a further 12 hoursat the boil under reflux. During this period hydrogen chloride andsulfur dioxide gas are-evolved. The hot pigment suspension is filteredwith suction, and the filter residue is washed with hot chlorobenzeneuntil the washings are colorless. The

residue :isithen thoroughly washed with hot alcohol and dried in vacuoat 60-70" C.

"The resulting dyestuff of the formula CH3 C H:

is a red powder which dissolves in concentrated sulfuric acid with apurple red coloration. It can be incorporated well into artificialplastics, for example, polyvinyl precipitates in the form of handsome,yellowish crystals.

The whole .is allowed to cool, filtered with suction and the filterresidue is washed with cold alcohol. After being dried, the product isobtained in the form of almost colorless lamellae having a fatty lustreand melting at 209-211 C.

carboxylic acid ethyles'ter and 2-hydroxynaphthalene-3- 40.4 parts ofthe resulting monohydrazideare dissolved with parts of sodium hydroxidesolution of 30 percent strength in 400 parts by volume of water. 60parts of crystalline sodiumacetate are added to the solution, and at 4 6C. a clear diazo' solution prepared from 37.5 parts of 4-chloro-2:5dimethoxy-l-aminobenzene is run in. In order to completethecoupling themixture is stirred for 4 hours at 5-10" 0., then heated to 40 C., andthe dyestufi formed is filtered oif and washed Well with warm water.After being dried in vacuo at C. it is obtained in the form of a darkpo'wderwhich dissolves in high boiling organic solvents with a violetcoloration. It dissolves in concentrated sulfuric acid with a reddishblue coloration.

40 parts of the resulting dyestu'fl? acid hydrazide are stirred with40.5"parts of the dyestulf acid chloride, obtained by treating the azodyestuff from diazotized 4-chloro-2:5dimethoxy-l-aminobenzene and2-hydroxytnaphthalene-kcarboxylic acid with thionyl chloride asdescribedin the first paragraph in Example 1 in 800 par-ts *by volurneofanhydrous chlorobenzene with the addition of 10 parts of -pyridine,andthe whole is heated at the boil for 8 hours under reflux. The mixture isthen allowed to cool to C., 30 parts of thionyl chloride are -added, andthe mixture is heated for a further 12 hours atlZO-BO" C. The hotsuspension is then filtered,

thefilter residue is washed with boiling chlorobenzene until thewashings are practically colorless, and it is then washed thoroughlywith hot alcohol anddried in vacuo at 6070 C. The resulting dyestufl. ofthe formula I ([)H OH 0 CH3 Cl-QN:

OGHa

. Example 4 38.25 parts ofthe dyestufii acide chloride of the formulaHtCiO 0 C O H obtained by treating the dyestutf from 'l-aminobenzene-2-of hydrazine sulfate and 20 parts of pyridine in 400- parts ofnitrobenzene, and the mixture is heated to CzHsOOC a 7 ISO-140 C. Thehydrazine condensation .product separates in the form of bright redcrystals from the dark red solution. The whole is stirred for 6 hours atthat temperature, and is then allowed to cool to 70 C. and 30 parts ofthionyl chloride are added. The mixture is heated for a further 12 hoursat 130-140" C. The crystalline form of the hydrazine condensationproduct gradually disappears, and a fine bright red suspension isformed. The suspension is filtered hot, and the filter residue is washedwith hot nitrobenzene, then .with hot benzene and finally with hotalcohol, until the washings are colorless, and the product is dried invacuo at 60-70 C.

The resulting dyestulf of the formula COOCIHG is a bright red powderwhich dissolves in concentrated sulfuric acid with a red violetcoloration. When incorporated by rolling in polyvinyl chloride itproduces strong pure red tints of very good fastness to migration andexcellent fastness to light.

Example 35.45 parts of the dyestufi of the formula CH: OH

obtained by coupling diazotized 1-amino-2-methyl-4- chlorobenzene with2-hydroxynaphthalene-3-carboxylic acid hydrazide, are heated in 500parts by volume of chlorobenzene with 5 parts of pyridine and 7.65 partsof fumaric acid chloride for 8 hours at 120-130 C. The suspension isthen allowed to cool to 70 C., parts of thionyl chloride are added, andthe whole is heated for a further 12 hours at 120-130 C. The dyestuffformed is then filtered off with suction, washed with hot chlorobenzeneuntil the washings are almost colorless, then washed with hot alcoholand dried in vacuo at 60-70 C.

The resulting dyestufi of the formula 8 is a red powder which dissolvesin concentrated sulfuric acid with a bordeaux red coloration, and whichwhen incorporated in artificial plastics, especially in polyvinylchloride, yields strong red tints. The coloration in polyvinyl chlorideis fast to migration and has a very good fastness to light.

Example 6 32 parts of the dyestufi of the formula p gii5 b is a brightred powder, which dissolves in concentrated sulfuric acid with a redcoloration. When incorporated by rolling into polyvinyl chloride thedyestutf yields very pure scarlet red tints of excellent fastness tomigration and good fastness to light.

By using, instead of the dyestufi from diazotizedl-amino-Z-methylbenzene and 2-hydroxynaphthalene-3- carboxylic acidhydrazide, the dyestutf of the formula OH OH! and otherwise proceedingas described in example, is obtained in the form of a, loose yellowpowder which th'ere'is obtained the dyestufiof'the' formula dissolves inconcentrated'sulfuric acid with a reddish GR: I s v This'dyestufl 'is adark powder which dissolves in con- 7 yellow coloration. The dyestufi,when' incorporated by 'ce'nt ratedfsulfhric" acid' with agreenish bluecoloration, and when incorporated in: artificial plastics, especiallyrolling into polyvinyl chloride, yields pureyellow tints of goodfastness to migrationand light. t those composed of polyvinyl chloridecompounds, it yields By using, instead of the dyestuff from4-chloro-2z5- blue tints which are fast to migration.dimethoxy-l-acetoacetylaminobenzene and para-amino- I qm e 7 I I benzoicacid, the dyestufi obtained from the aforesaid 4 19.S, parts df t y lfifrQIIi diaZOfiZeIjl P chloro-3-aminobenzoic acid or4-methoxy-3-arninobenzoic ammobenzorc. acid and? 4=chloro-2/:5-d1me0X-Y- c acid, there is obtained a dyestuif having similar properties.acetylaminobenzene are stirred 1n 2000 parts of chlorobenzene with 150parts of thionyl chloride, and the whole is heated in an oil bath at 120C. The greenish yellow Example 8 paste becomes thinly liquid and changesinto a magma 411 am of th d tug hl f th f 1 of orange-yellow crystals.The whole is stirred for 4 p e yes ac] c on e 0 6 a hours at 120 C. Atthe end of this period the evolution of hydrogen chloride practicallyceases. The whole is OCHa E 01 then allowed to cool and is filtered withsuction. The I 0 I .filtencakeis washed; withbenzeneuntilthe washings.are 6 1 0 0 -N=N colorless. V After drying the product" in vacuo thereare obtained -l 5ipa1ft$of tlrerdyestulf. acid: chlorideofthe: formula.

, I 1 a o 1 OCH: 7 CITIHL C j (IJOH (melting at 253 254 C) are stirredin 1200 parts of 01 NHCO (L.'NN\O COCI toluene with 5 parts of hydrazinehydrate and the mixture CHI is heated to the boil in one hour. 100 partsof toluene in the form of g y needles meltmgjtat, 254 are distilled offuring WhlCh 18 parts or water distil 256 C. 43.9 parts of this acidchloride. are stirred! in 1000 parts of toluene with 5 parts. of-hydrazine hydrate and heated in the course of one hour to 110 C. 100parts of toluene are distilled ofi together with 1.8 parts of water. Thewater distilled off has an acid reaction to Congo. The reaction mixtureconsists mainly of the lution oi hydrogen chloride practically ceases.The mixsymmetrical dyestufi acid; hydrazide and hydrazine ture 1s'thenallowed to cool to 80 C. and 20 parts by vol-- dmchloride The whole isallowed to cool to 9 c ume of-thronyl chlonde are added. The mixture isagain and a f th 433 parts f d fl-j acid chloride are 5 heated'to the,boil and boiled for 12 hours under reflux.

further"42.1 parts of the acid chloride are added. The whole isthenboiled for 6 hours under reflux, during which the orange-yellowchloride rapidly disappears and a greenish yellow suspension is formed.After 6 hours the evof T e h r heated the l f 6 The dyestuif' formed isfilteredofi while hot and the filter hours, during which hydrogenchloride is evolved, A1; residue is Washed with boiling toluene untilthe washings the end fflfi period th o d tion i om lete, d arecolorless. After drying the product in vacuo at the mixture" re allowedto cool to C. 20 parts by 70 C. there is obtained in very-good yield thedyest'uif of volume of :thionyl chloride are then added and the mix- 55the formula CH3 OCHs C1, r 01- NBC 00N=N- or C- l l l CH3 ture is boiledfor 12 hours under reflux. fDuring, the in theforrn of a loose-greenishyellow. powder'which first few hours hydrogen chloride and sulfurdioxide are consists of microscopically .srnall very fine needles. The

evolved-. Tlie mixture'isfiltered with suction while hot 65 dyestuiidissolves in concentrated sulfuric acid with a toremove'thedyestuifformed, and. the latter.iswashed yellow coloration.When. incorporated by rolling into j with hot' folueneuntil' thewashings'are colorless. polyvinylchloride it produces puregreenishayellow tints After being dried in vacuo the dystufi'of theformula of excellent fastness to migration and light.

CH; v C

. I OCH! ton coupling component and meta-aminobenzoic acid, 4-

overt The/whole is-thenallowedto cool to ,C. and a p I v Example9 X H142.? parts of thedyestutf acid chloride of the formula on; c1 N01.

(melting with decomposition at 261-262" C.) are stirred to 80 C. andparts by volume of thionyl chloride are added. The mixture is againheated to the gentle boil and boiled for 12 hours under reflux. Thedyestuff formed is filtered ofi while hot and washed with boilingtoluene until the washings are colorless. After being dried, the

. dyestufi of the formula is obtained in good yield in the form of aloose yellow powder which dissolves in concentrated sulfuric acid with ayellow coloration. When incorporated in polyvinyl chloride foils, ityields gold yellow tints which are fast to migration and light.

Example 10 443 parts of the azo-dyestutf from diazotizedl-aminobenzene-Z-carboxylic acid butyl ester and 4-methoxy-3-acetoacetylamino-benzoic acid are stirred in 2500 parts of benzene with150 parts of thionyl chloride and the mixture is slowly heated to theboil. At 80 C. the dyestuff dissolves. Stirring is continued for afurther hour at that temperature and then the mixture is allowed tocool, whereupon the acid chloride crystallizes out in the form of smallpale yellow needles. The crystals are filtered off with suction, washedwith a small amount of cold benzene and petroleum ether, and dried invacuo at 60-70 C. There are obtained 385 parts of the dyestufi acidchloride of the formula melting at 168-169 C.

12 46.15 parts of this acid chloride are stirred in 1200 parts oftoluene with 5 parts of hydrazine hydnte snd heated to the boil in onehour. 100 parts of toluene are distilledofi together with 1.8 parts ofwater. The whole is then allowed to cool to 90 C. and a further 46.15parts of the acid chloride are added. Boiling under refluxis continuedfor 6 hours. At .theend of this period the evolution of hydrogenchloride practically ceases. The whole is allowed to cool to 80 C. and20 parts by volume of thionyl chloride are added, and boiling'underreflux is continued for a further 12 hours. The dyestufi formed isfiltered off while hot, and washed with hot toluene. After beingdried,the dyestufi of the formula CHI Lh't

is obtained'in the form of a bright yellow powder, which whenincorporated in artificial plasn'cs, especially in composed of polyvinylchloride, yields very greenishyellow tints having good properties offastness.

NO! N0, a} Cl 0 0H t Y Y a 7. l i ii p l Example 1 I 39.95 parts of thedyestufi acid'chloride are added. The mixture is then boiled for 6 hoursunder reflux, during which a strong evolution of hydrogen chloride isobserved at the outset. At the end of this periodth'e mixture is conOahu-(Lo can? our allowed to cool to C., and 20 parts by volume ofthionyl chloride are added. The whole is then boiled for 19 hours underreflux. The mixture is filtered hot and the filter cake is washed withboiling toluene and with hot alcohol until the washings are completelycolorless, After 13 14 v being dried in vacuo at 60-70 C., the dyestufiof the in which n represents a'whole number of at the most 2, formula vR represents a hydrocarbon radical having at least 2 NO: I NO:

a loose yellow-orange powder which dissolves in conand at the most 6carbon atoms, and R and R 'each centrated sulfuric acid with a yellowcoloration and 15 represents a member selected from the group consistingwhen incorporated in artificial plastics, especially in polyof radicalscorresponding to the formulae vinyl chloride yields powerful orangetints which are fast to light. and 2 Example 12 42.0 parts of thedyestufi acid chloride of the formula 01 a GM a v g p g 7 H4 7 I v g; inwhich R is anacetoacetylaminobenzene radical, each of R and R' is anaromatic radical containing a single which melts at 180-5132 are surfedIn 1200 Paris ring which is a six-membered carbocyclic ring, and R" oftoluene with 5 parts of hydrazine hydrate and the i a pyrazolone di Lwhole is heated to the b i in 0116 1101111 100 Parts of 2. An azopigment which is free from water-solubiliztoluene are distilled offtogether with 1.8 parts of water. in groups d corresponds to th for ulaThe whole is then allowed to cool to 90 C. and a further H0 0H 42.0parts of the dyestuff acid chloride are added. The O I o 1 mixture isthen boiled for 6 hours under reflux, allowed to cool to 80 C., and 20parts by volume of thionyl ll II I I ll chloride are added. The whole isthen boiled under reflux for 12-15. hours, and the dyestuff formed isfiltered oif while hot, and washed with hot toluene and hot alcoholuntil the washings are colorless. After drying the product in vacuo,there is obtained in very good yield the y "-1 dyestuif of the formulain which n represents a Whole number of at the most I in the form of aloose, yellow-orange powder which dis- 2, R' represents an aromaticradical containing a single solves in concentrated sulfuric acid with ayellow coloraring which is a sixmembered carbocyclic ring and R4 tion.When incorporated into artificial plastics, especially re resents a hdro a be h t in polyvinyl chloride, it yields clear reddish yellow tintsatpthe most 6 Z g g lcal avmg at least 2 and whlch are fast t9 mlgranonand hght' 3. An azo pigment which is free from water-solubiliz- Example13 ing groups and corresponds to the formula parts of polyvinylchloride, 35 parts of dioctylphthalate and 0.5 part of the disazodyestuif obtainable as described in Example 1 are stirred together, andthe H0 I OH resulting mixture is then passed to and fro between the 65two rollers of a calender for about 3 minutes at 140- R"'N=N c 0N:-=N'---1z."'v 145 C. There is obtained a pure red colored foil whichis strongly colored and has a very good fastness to light and migration,

What is claimed is: 1. An azo pigment which is free fromwater-solubilizing groups and corresponds to the formula RO/ o'lRr-c c min which R' represents an aromatic radical containing i g L H U U asingle six-membered ring which is a carbocyclic ring.

1 5 1 6 4. The ezo pigment of the formula om V y no 2 c1 c1 6 003. g moo/C-N=N I c N=NC\ O NH-E CHN 01 H1 CH. 5. The azo pigment of the formula10 7. The azo pigment of the formula OH: HO OH H30 0 o (Lo-0,11; no onEcho-t c N-N f: N=N cl 0 1$ r5 c c N=N 6. The azo pigment dfthe formula00B: HO OH H100 2,628,230 Stihnar Feb. 10, 1953 FOREIGN PATENTS 929,498Germany June 27, 1955 0 I References Cited in the file of this patent cN=N N=N 01 UNITED STATES PATENTS H c CH 2,616,891' Schwechte'n et a1.Nov. 4, 1952

1. AN AZO PIGMENT WHICH IS FRE FROM WATER-SOLUBILIZING GROUPS ANDCORRESPONDS TO THE FORMULA